A vehicle floor of a passenger car generally has a base plate, to which a soundproofing floor covering is applied. In more luxurious passenger cars, an air-conditioning duct is laid in this floor covering, the duct having a duct outlet which opens into the vehicle rear and serving to carry conditioned air from an air-conditioning device of the vehicle into the vehicle rear.
However, such an air-conditioning duct also allows sound to enter the rear area of the vehicle interior, the sound entering in the region of air-inlet openings to the air-conditioning device, for example, or being produced in the air-conditioning device itself, e.g. by a fan motor. To reduce this rise in the noise level in the vehicle interior caused by the air-conditioning duct, EP 0 338 908 B1 discloses the provision of a soundproofing layer of foam on both the inside and the outside of a rigid-plastic core of the air-conditioning duct.